Harkening back to the Rourouni Kenshin series Suzume and Ayumi were mischievous and amusing and cute all at once. It was a good idea to add them to that anime to bring out more of kenshin's character as a declared uncle to them. "Wheres Uncle Ken? He said he would play with us!

Hard to pick a favorite, there`s so many cute ones hehe.
My favorite of the summer season is Hinata-chan, Koala Attack ftw :D
Favorite imouto characther is Chiaki Minami, she is awesome.
Favorite all time, actually I think that`ll be Hinata-chan too.
Hitoha from Mitsudomoe is great too.